230v line to neutral single phase IEC motor

[Besoeker]

Then how or why does a 480 volt 60Hz motor produce less torque on 400 volts 60Hz?

I think this not a standard induction so the rules of engagement change. The two ratings for power are a bit of a clue.

 

[mbrooke]

I think this not a standard induction so the rules of engagement change. The two ratings for power are a bit of a clue.

It could be typical, be just rated differently. That fact the PF gets so high leads me to think this is built more around 50Hz but with a 60Hz rating just tossed in. Not that this could effect the OP however. In my limited experience motors are often over sized for the application when driving belts, fans, ect.


EDIT: the current is also more at 60 Hz...

 

[mbrooke]

Here is a pic of a similar motor I dealt with in a similar application for discussion purposes. Note the differences in rating:

 

[Besoeker]

thanks
rated shaft P
50 Hz 1.5 kw or 2 HP
60 1.8 kw or 2.4 HP
so fully rated at 60

Torque
50 Hz 7.25 lb-ft
60 Hz 7.3 lb-ft
essentially the same
so torque remains constant

shaft P = v x i x pf x eff (v x i = electrical power)
eff = Shaft P / (v x i x pf)
50 Hz 80%
60 Hz 79%

Now, having seen the nameplate, you could have done that a lot more simply.
The power is proportional to speed in both cases.
That can only happen with constant torque.

No need to make it any more complex than that.

 

[Ingenieur]

Look at the cos phi. What does that tell you?

var increase because Xc decreases which improves pf since var = V^2 / Xc
small compared to the decrease in Z
230/8.4 = 27.4 Ohm (total R, Xl, Xc)
230/10 = 23 Ohm
27.4/23 ~ 1.2 or 20%

Cd
50 Hz 26.5
60 Hz 22.10
20% decrease, current increases 20% (8.4 x 1.2 ~ 10 A)
(Xl not included)

do you always answer a ? with a ? or do you ever actually ANSWER a ? ?
lol

 

[Ingenieur]

Now, having seen the nameplate, you could have done that a lot more simply.
The power is proportional to speed in both cases.
That can only happen with constant torque.

No need to make it any more complex than that.

not true
why is it constant?
you lack understanding
you are not alone

power is power lol

 

[Ingenieur]

Here is a pic of a similar motor I dealt with in a similar application for discussion purposes. Note the differences in rating:

at 50 Hz i is greater in this case
the other motor the inverse it true

 

[iwire]

you lack understanding
you are not alone

Before things escalate, I ask all to refrain from commenting on the each other and stick with the actual topic.

 

[Ingenieur]

Before things escalate, I ask all to refrain from commenting on the each other and stick with the actual topic.

that is what I was doing
trying to illustrate why power is proportional to speed in this case

 

[Besoeker]

var increase because Xc decreases which improves pf since var = V^2 / Xc
small compared to the decrease in Z
230/8.4 = 27.4 Ohm (total R, Xl, Xc)
230/10 = 23 Ohm
27.4/23 ~ 1.2 or 20%

Cd
50 Hz 26.5
60 Hz 22.10
20% decrease, current increases 20% (8.4 x 1.2 ~ 10 A)
(Xl not included)

do you always answer a ? with a ? or do you ever actually ANSWER a ? ?
lol

I wasn't answering a question. I was asking one.

 

[mbrooke]

Now, having seen the nameplate, you could have done that a lot more simply.
The power is proportional to speed in both cases.
That can only happen with constant torque.

No need to make it any more complex than that.

Then why does my nameplate contradict the OPs?

 

[mbrooke]

at 50 Hz i is greater in this case
the other motor the inverse it true

But why is that? Aren't the physics the same?

 

[Ingenieur]

I think this not a standard induction so the rules of engagement change. The two ratings for power are a bit of a clue.

it IS a standard 1 ph induction motor
not a constant torque motor (intentionally)
can't mix 1 ph and 3 ph
1 ph has capacitors whose X changes with freq, lowering Z, therefore increasing I for a constant v
power increases due to I increase
but speed increases which gives back the gain

 

[iwire]

that is what I was doing
trying to illustrate why power is proportional to speed in this case

I am sure you can, and could have, done so without any opinions about what others may or may not know.

 

[mbrooke]

it IS a standard 1 ph induction motor
not a constant torque motor (intentionally)
can't mix 1 ph and 3 ph
1 ph has capacitors whose X changes with freq, lowering Z, therefore increasing I for a constant v
power increases due to I increase
but speed increases which gives back the gain

Of course, gain by mathematical multiplication of two finalized concepts. But starting torque is just that: torque with no speed. Increasing the frequency causes the magnetic field to spin faster, but with a reduced density provided voltage stays that same. Its that density which is responsible for torque.

 

[Ingenieur]

I wasn't answering a question. I was asking one.

you were responding to my ASKING a question

 

[Ingenieur]

Of course, gain by mathematical multiplication of two finalized concepts. But starting torque is just that: torque with no speed. Increasing the frequency causes the magnetic field to spin faster, but with a reduced density provided voltage stays that same. Its that density which is responsible for torque.

I was not describing the EM mechanism that generates torque
but the relationship of shaft torque based on varying speeds (and in this case Xc)

 

[Ingenieur]

I am sure you can, and could have, done so without any opinions about what others may or may not know.

you mean like he did?
gotcha

 

[mbrooke]

I was not describing the EM mechanism that generates torque
but the relationship of shaft torque based on varying speeds (and in this case Xc)

I can understand that, but I still maintain the its only part of the picture.

 

[Ingenieur]

I can understand that, but I still maintain the its only part of the picture.

not for what we are discussing
a motor driving a load

if we know: v, I, pf, eff we know shaft power
does not matter what is going on in the motor (that is reflected in the above data)
add in rpm we know torque

from this we can determine the force on a belt
the volume/head capabilities of a pump
etc.